Siemens WL family of circuit breakers has been designed to
address the increasingly demanding requirements of today’s electrical power distribution systems and incorporates the following characteristics.
• High reliability • Compact size • Ease of use
• Modularity of design
• Flexibility of system communications • Safety-oriented features
The circuit breakers discussed thus far in this course are molded case circuit breakers that conform to the UL 489 specification. This specification also covers a category of molded case circuit breaker commonly referred to as an insulated case circuit breaker (ICCB). ICCBs are generally used in switchboards and
may be fixed-mounted or drawout-mounted.
Another category of large circuit breakers is the low voltage (LV) power circuit breaker. LV power circuit breakers are
generally drawout-mounted and may be used in switchboards or switchgear. LV power circuit breakers intended for the U.S. market conform to American National Standards Institute (ANSI) standards (C37.3, C37.6, C37.7, and C37.50) and National Electrical Manufacturers Association (NEMA) standard SG3. The corresponding UL specification for LV power circuit breakers is UL 066.
Siemens WL family of circuit breakers includes both ICCBs that conform to the UL 489 specification and LV power circuit breakers that conform to UL 066 and corresponding ANSI and NEMA specifications.
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Modularity of Design As previously mentioned, one of the important characteristics of the WL family of circuit breakers is its modularity of design. The following illustration identifies the array of trip units, options, and accessories for use with WL circuit breakers.
2 1 3 4 5 6 7 8 9 10 11 12 13 14 15 17 16 19 20 21 22 23 24 25
1. Guide Frame (for drawout version) 2. Vertical to Horizontal BUS Connector 3. Position Signaling Switch
4. Breaker/Guide Frame Grounding Contact 5. Shutter (locking)
6. Modbus or Profibus Communications 7. External CubicleBUS I/O Module 8. Plug-in Open and Closed Solenoids 9. Multiple Secondary Connections 10. Auxiliary Switch Block 11. Door Sealing Frame 12. Interlocking Set Base Plate
13. Protective Cover for OPEN/CLOSE Buttons
14. Emergency-Stop Pushbutton, Key Operated 15. Single Bolt Motor Operator Installation 16. Operating Cycles Counter
17. Breaker Status Sensor (BSS) 18. Electronic Trip Unit (ETU) Family 19. Reset Solenoid
20. Breaker Data Adapter (BDA) 21. Four-line LCD Module 22. Ground-fault Function Module 23. Rating Plug
24. Metering Function Module 25. Circuit Breaker
WL UL 489 Circuit Breakers WL UL 489 circuit breakers have a rated maximum operating
voltage of 600 V and are available in three frame sizes with frame ratings from 800 to 5000 A. All three frame sizes have fixed-mounted and drawout-mounted versions.
Frame Size I Frame Size II Frame Size III
O I
O I
O I
Rated Nom inal Current
Rating Class S H L S H L
Interrupting Current (Ics) at 240 V 65,000 85,000 100,000 65,000 85,000 100,000
Interrupting Current (Ics) at 480 V 65,000 85,000 100,000 65,000 85,000 100,000
Interrupting Current (Ics) at 600 V 65,000 65,000 65,000 65,000 65,000 65,000
Rated Nom inal Current
Rating Class S H L S H L
Interrupting Current (Ics) at 240 V 65,000 85,000 100,000 65,000 85,000 100,000
Interrupting Current (Ics) at 480 V 65,000 85,000 100,000 65,000 85,000 100,000
Interrupting Current (Ics) at 600 V 65,000 85,000 65,000 65,000 85,000 65,000
Rated Nom inal Current
Rating Class S L C S L C S L C
Interrupting Current (Ics) at 240 V 65,000 100,000 150,000 65,000 100,000 150,000 65,000 100,000 150,000
Interrupting Current (Ics) at 480 V 65,000 100,000 150,000 65,000 100,000 150,000 65,000 100,000 150,000
Interrupting Current (Ics) at 600 V 65,000 85,000 100,000 65,000 85,000 100,000 65,000 85,000 100,000
Rated Nom inal Current
Rating Class S L C L C L C
Interrupting Current (Ics) at 240 V 65,000 100,000 150,000 100,000 150,000 100,000 150,000
Interrupting Current (Ics) at 480 V 65,000 100,000 150,000 100,000 150,000 100,000 150,000
Interrupting Current (Ics) at 600 V 65,000 85,000 100,000 85,000 100,000 85,000 100,000
Rated Nom inal Current
Rating Class L C L C
Interrupting Current (Ics) at 240 V 100,000 150,000 100,000 150,000
Interrupting Current (Ics) at 480 V 100,000 150,000 100,000 150,000
Interrupting Current (Ics) at 600 V 85,000 100,000 85,000 100,000
Note: Interrupting Current in Sym etrical RM S Am peres
1200 A Fram e Size I
Fram e Size I
1600 A Fram e Size II
Fram e Size III
4000 A 5000 A Fram e Size II 2000 A 2500 A 3000 A 800 A 1600 A 2000 A 800 A 1200 A
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WL UL 1066 Circuit Breakers WL UL 1066 circuit breakers are generally used in low voltage
(LV) switchgear as drawout-mounted breakers, have a rated maximum operating voltage of 635 V, and are available in two frame sizes with frame ratings from 800 to 5000 A.
One important LV power circuit breaker rating is its short- time withstand current rating. This rating indicates the level of current that a breaker can handle without damage for a designated short time. This rating is important because an LV power circuit breaker is often required to delay tripping for a short time when a fault current is sensed so that a downstream breaker closer to the fault has time to trip, thereby avoiding a larger system outage.
Rated Nominal Current
Rating Class N S H L F N S H L F
Interrupting Current (Ics) at 254 V 50,000 65,000 85,000 100,000 200,000 50,000 65,000 85,000 100,000 200,000
Interrupting Current (Ics) at 508 V 50,000 65,000 85,000 100,000 200,000 50,000 65,000 85,000 100,000 200,000
Interrupting Current (Ics) at 635 V 50,000 65,000 65,000 85,000 200,000 50,000 65,000 65,000 85,000 200,000
Short-time Withstand Current (Icw) for 0.5 sec. 50,000 65,000 65,000 85,000 -- 50,000 65,000 65,000 85,000 --
Rated Nominal Current
Rating Class S H L F S H L
Interrupting Current (Ics) at 254 V 65,000 85,000 100,000 200,000 65,000 85,000 100,000
Interrupting Current (Ics) at 508 V 65,000 85,000 100,000 200,000 65,000 85,000 100,000
Interrupting Current (Ics) at 635 V 65,000 65,000 85,000 200,000 65,000 65,000 85,000
Short-time Withstand Current (Icw) for 0.5 sec. 65,000 65,000 85,000 20,000 65,000 65,000 85,000
Rated Nominal Current
Rating Class M F H L M F H L M F
Interrupting Current (Ics) at 254 V 150,000 200,000 85,000 100,000 150,000 200,000 85,000 100,000 150,000 200,000
Interrupting Current (Ics) at 508 V 150,000 200,000 85,000 100,000 150,000 200,000 85,000 100,000 150,000 200,000
Interrupting Current (Ics) at 635 V 85,000 200,000 85,000 85,000 85,000 200,000 85,000 85,000 85,000 200,000
Short-time Withstand Current (Icw) for 0.5 sec. 100,000 1 -- 85,000 100,000 1100,000 1 -- 85,000 100,000 1100,000 1 --
1. Do not apply breaker at 635 V on a system with available fault current greater than 85KA RMS. 2. Interrupting Current and Short-time Withstand Current in Symetrical RMS Amperes
2000 A 3200 A
3200 A 4000 A 5000 A
Frame Size III Frame Size II
800 A 1600 A
Frame Size II
Frame Size II Frame Size III
O I
WL Circuit Breaker WL circuit breakers can be fused or unfused and delivered with
Operating Mechanisms any of these operating mechanisms:
• Manual operating mechanism with mechanical closing (standard)
• Manual operating mechanism with mechanical and electrically interlocked closing
• Motorized operating mechanism with mechanical and electrically interlocked closing.
Exterior Features WL circuit breakers have a number of standard and optional
features that enhance the safety and usability of the breaker, reduce errors, and minimize training time. The following illustration, shows some of the features that can be seen from the front.
CubicleBUSintegrated
RESET BREAKER TRIPPED FUSE TRIPPED
= 12 g Rating Plug OFF ON 1 1 1 1 1 SI ETU745 AUTO OFF MOTOR OK CHARGED OPEN
CONTACTS READY SPRING
OPEN PUSH TO CLOSE
!WARNING !DANGER UL LISTED SA 99993 DISCON TEST CONNECT Locking Device
”lock OPEN” (option) Motor Disconnect Switch (option)or “Electrical Closed” (option)
Trip Unit
Racking Handle Lock (option) Mechanical Release of Racking Handle (option)
“OPEN” Button or “EMERGENCY OPEN” Mushroom Button (option)
Circuit Breaker OPEN/CLOSED Indicator Ready-to-close Indicator Stored-energy Indicator “CLOSE” Button
Handle Position Indicator Racking Handle
Padlock Capable Spring Charging Lever Make-break Operations
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WL Electronic Trip Units Three electronic trip units are available for use with WL circuit breakers. The protective functions and additional capabilities available for these trip units are shown in the accompanying diagram. A few of these features are briefly described in the paragraphs that follow this diagram.
Long time pickup and delay-overload protection (L) ● ● ●
Short circuit protection-short-time delayed (S) ● ● ●
Short-circuit protection-instantaneous (I) ● ● ●
Neutral conductor protection (N) ● ● ●
Ground fault protection (G) o o o
Alphanumeric LCD o o - Graphical LCD - - ● CubicleBUS ● ● ● PROFIBUS-DP o o o MODBUS o o o Ethernet (BDA) o o o
Selectable neutral protection ● ● ●
Defeatable short-time delay ● - ●
Defeatable instantaneous protection ● - ●
Selectable thermal memory ● ● ●
Zone selective interlocking ● ● ●
Selectable I2t or fixed short-time delay ● ● ●
Adjustable instantaneous pick-up ● - ●
Selectable I2t or I4t long-time delay ● ● ●
Adjustable short-time delay and pick-up ● ● ●
Selectable and adjustable neutral protection ● ● ●
Dual parameter sets A and B - - ●
Dynamic arc-flash sentry (DAS) - - ●
Extended instantaneous protection (EIP) ● ● ●
Parameterization by rotary switches ● ● -
Parameterization by communication (absolute values) - - ●
Parameterization by menu/keypad (absolute values) - - ●
Remote parameterization the basic functions - - ●
Remote parameterization of the additional functions - - ●
Metering function o o o
Metering function plus o o o
Additional Functions Communication
Basic Protective Functions
Display
● = standard, o = optional
ETU745 ETU748 ETU776
The switch-selectable I2t or I4t characteristic curve function allows the breaker’s long-time characteristics to be set to either an I2t curve or an I4t curve to make it easier to achieve optimal coordination.
Dual parameter sets simplify adapting the system to rapid
changes, such as when power is switched between utility power and a generator. Switching between parameter sets can be done quickly and, if desired, remotely.
Dynamic Arc-Flash Sentry (DAS) employs the unique dual protection settings of ETU776 trip units coupled with the ability to toggle to a lower arc flash parameter set. A normal parameter set can be optimized for selective trip coordination with the alternate parameter set optimized for lower arc flash energy levels initiated when personnel approach the arc flash protection boundary.
Extended Instantaneous Protection (EIP) is designed to provide any WL low voltage power circuit breaker with the capability to be applied at the short-time withstand rating of the breaker with no instantaneous override. This feature gives downstream breakers the maximum possible time to clear a fault and reduces the likelihood of a system-wide outage.
Trip Unit Modularity The modularity of WL circuit breakers extends to the electronic trip units (ETUs). For example, any ETU model can be installed in any WL circuit breaker. In addition, selected ETU models can be easily adapted to changing conditions in the field by the addition or replacement of the following ETU modules: • Display
• Ground fault protection • Rating plug
• Metering function/metering function plus • Communication = 12 g Rating Plug OFF ON 1 1 1 1 1 SI ETU745
Option: lock prevents unathorized resetting of the mechanical trip indicator after a trip Local Mechanical RESET
or optional remote RESET with optional reclosing lockout
Sealing ring Overcurrent alarm
Indicator: trip cause Rating plug
Ground fault pick-up setting Neutral conductor protection on/off Communication active
Indicators Option: Alphanumeric display Scroll down
Thermal memory on/off Setting value
Neutral conductor overload
Indicator: Ground-fault trip Indicator: Ground-fault alarm Option: Ground-fault module Selectable overload long-time characteristic (I2t/I4t)
Mechanical trip indicator
Scroll up Trip unit active
Extended alarm fuction active Long-time pick-up setting Short-time pick-up setting Instantaneous pick-up setting Ground fault mode selector Ground fault pick-up setting Ground fault alarm setting
Trip unit error
Long-time delay setting Short-time delay setting
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The alphanumeric LCD display is an option for ETU745 (shown in the previous graphic) and ETU748. ETU776 comes equipped with a graphical LCD display.
Ground fault trip and alarm and ground-fault-only modules are available for ETU745, ETU748, and ETU776.
The rating plug is a replaceable module used to set the continuous current rating for the circuit breaker. Rating plugs are available for frame size II from 200 to 3200 amps and for frame size III from 800 to 5000 amps.
The integrated metering function can be installed on ETU745, ETU748, and ETU776 to measure currents, voltages, power, energy, power factor, and frequency. All metered quantities are real-time values with min/max recording. The metering module also provides additional alarm setpoint and protective relay functions. The metering function plus module has additional recording capacity and supports harmonic analysis.
Communication Options A variety of communications capabilities are available for WL circuit breakers. CubicleBUS forms the backbone of this system. CubicleBUS is an internal system bus that connects all intelligent components in the WL circuit breaker and simplifies the
connection of external components.
3 1 4 8 9 10 11 12 14 5 6 7 2 PROFIBUS DP Ethernet CubicleBUS 1. WL Circuit Breaker
2. COM15 PROFIBUS module 3. Breaker Data Adapter (BDA) 4. BDA Plus with Ethernet Interface 5. Breaker Status Sensor (BSS) 6. Electronic Trip (ETU) 7. Metering Function
8. Zone Selective Interlocking (ZSI) Module 9. Digital Output Module with Rotary Switch 10. Digital Output without Rotary Switch 11. Analog output module
12. Digital Input Module
13. Power Meter with PROFIBUS DP Communication 14. Programmable Logic Controller (PLC)
CubicleBUS is incorporated into all WL circuit breakers with ETU745, ETU748, and ETU776 trip units. The modular design of this system simplifies retrofitting of communications functions. All modules shown attached to CubicleBUS in the previous illustration directly access the available data of the circuit breaker.
With the addition of a COM5 PROFIBUS module for
PROFIBUS DP communications or COM6 Modbus module (not shown) for Modbus RTU communications, WL circuit breakers with ETU745, ETU748, and ETU776 trip units can have ETU parameters changed and the breaker can be opened and closed remotely. In addition, data can be shared with other systems. For trip units with the metering function or metering function plus option, the breaker can take on an even wider role in a power management system.
The Breaker Data Adapter (BDA) incorporates configuration software and embedded web pages and can be connected to a laptop or other computer running a web browser. This provides the capability for online configuration and diagnostics or for configuration data developed offline to be downloaded to the trip unit or printed for reference. The BDA Plus has all the functionality of the BDA and can also connect to an Ethernet network.
CubicleBUS I/O Modules As previously indicated, a variety of CubicleBUS input/output (I/O) modules are available to expand the capabilities of the WL circuit breaker. The following brief descriptions summarize the capabilities of these modules.
The digital output module with rotary switch allows up to six binary signals to be connected to external signaling devices or used to control other equipment. Solid-state and relay output versions of this module are available.
The digital output module without rotary switch allows up to six binary signals to be triggered by protective or setpoint events. However, three of these outputs can be assigned in a logical-OR arrangement connected to up to six events. Solid-state and relay output versions of this module are available.
The analog output module can be used to output a variety of measured values (amps, volts, power, power factor, etc.) to analog display devices on the cubicle door. Up to two modules
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The digital input module can connect to a maximum of six
digital (24 VDC) inputs. This enables the status of a switch or the cubicle door to be communicated to the circuit breaker.
Zone selective interlocking (ZSI) is a method that allows two or more circuit breakers to communicate with each other so that a short circuit or ground fault is cleared by the breaker closest to the fault in the minimum time. The ZSI module is used to interconnect WL circuit breakers in this arrangement.
Review 8
. Siemens WL circuit breaker family includes insulated case circuit breakers that conform to the UL ________ specification and LV power circuit breakers that conform to the UL ________ specification.
2. WL insulated case circuit breakers are available in both ________-mounted and ________-mounted versions. 3. WL circuit breakers are available in frame ratings from
________ amps to ________ amps.
4. The graphical LCD display is a standard feature of the ________ model trip unit.
5. ________ employs the unique dual protection settings of ETU776 trip units coupled with the ability to toggle to a low arc flash parameter set.